Search Publications
The merger that led to the formation of the Milky Way's inner stellar halo and thick disk
Brown, Anthony G. A.; Helmi, Amina; Babusiaux, Carine +3 more
The assembly of our Galaxy can be reconstructed using the motions and chemistry of individual stars1,2. Chemo-dynamical studies of the stellar halo near the Sun have indicated the presence of multiple components3, such as streams4 and clumps5, as well as correlations between the stars' chemical abundance…
A dynamically young and perturbed Milky Way disk
Figueras, F.; Evans, D. W.; Helmi, A. +10 more
The evolution of the Milky Way disk, which contains most of the stars in the Galaxy, is affected by several phenomena. For example, the bar and the spiral arms of the Milky Way induce radial migration of stars1 and can trap or scatter stars close to orbital resonances2. External perturbations from satellite galaxies can also …
A galaxy lacking dark matter
Mowla, Lamiya; van Dokkum, Pieter; Romanowsky, Aaron J. +9 more
Studies of galaxy surveys in the context of the cold dark matter paradigm have shown that the mass of the dark matter halo and the total stellar mass are coupled through a function that varies smoothly with mass. Their average ratio Mhalo/Mstars has a minimum of about 30 for galaxies with stellar masses near that of the Milky…
The onset of star formation 250 million years after the Big Bang
Ouchi, Masami; Harikane, Yuichi; Inoue, Akio K. +21 more
A fundamental quest of modern astronomy is to locate the earliest galaxies and study how they influenced the intergalactic medium a few hundred million years after the Big Bang1-3. The abundance of star-forming galaxies is known to decline4,5 from redshifts of about 6 to 10, but a key question is the extent of star formation …
Helium in the eroding atmosphere of an exoplanet
Ehrenreich, D.; Udry, S.; Bourrier, V. +20 more
Helium is the second-most abundant element in the Universe after hydrogen and is one of the main constituents of gas-giant planets in our Solar System. Early theoretical models predicted helium to be among the most readily detectable species in the atmospheres of exoplanets, especially in extended and escaping atmospheres1. Searches for…
Macromolecular organic compound s from the depths of Enceladus
Postberg, Frank; Trieloff, Mario; Schmidt, Jürgen +18 more
Saturn's moon Enceladus harbours a global water ocean, which lies under an ice crust and above a rocky core. Through warm cracks in the crust a cryo-volcanic plume ejects ice grains and vapour into space that contain materials originating from the ocean. Hydrothermal activity is suspected to occur deep inside the porous core, powered by tidal diss…
Observations of the missing baryons in the warm-hot intergalactic medium
Piro, L.; Shull, J. M.; Fiore, F. +18 more
It has been known for decades that the observed number of baryons in the local Universe falls about 30-40 per cent short1,2 of the total number of baryons predicted3 by Big Bang nucleosynthesis, as inferred4,5 from density fluctuations of the cosmic microwave background and seen during the first 2-3 billion years o…
Galaxy growth in a massive halo in the first billion years of cosmic history
Bayliss, M. B.; Béthermin, M.; Murphy, E. J. +34 more
According to the current understanding of cosmic structure formation, the precursors of the most massive structures in the Universe began to form shortly after the Big Bang, in regions corresponding to the largest fluctuations in the cosmic density field. Observing these structures during their period of active growth and assembly—the first few hu…
Rotation in [C II]-emitting gas in two galaxies at a redshift of 6.8
Holwerda, Benne W.; Carniani, Stefano; Maiolino, Roberto +10 more
The earliest galaxies are thought to have emerged during the first billion years of cosmic history, initiating the ionization of the neutral hydrogen that pervaded the Universe at this time. Studying this ‘epoch of reionization’ involves looking for the spectral signatures of ancient galaxies that are, owing to the expansion of the Universe, now v…
A massive core for a cluster of galaxies at a redshift of 4.3
Béthermin, M.; Murphy, E. J.; Greve, T. R. +35 more
Massive galaxy clusters have been found that date to times as early as three billion years after the Big Bang, containing stars that formed at even earlier epochs1-3. The high-redshift progenitors of these galaxy clusters—termed `protoclusters'—can be identified in cosmological simulations that have the highest overdensities (greater-th…